Field of the Invention
Exemplary embodiments of the present disclosure relate to a hybrid power generation system using a supercritical CO2 cycle, and more particularly, to a hybrid power generation system using a supercritical CO2 cycle, capable of removing an air preheater of a thermal power plant by means of using a supercritical CO2 cycle.
Description of the Related Art
Internationally, the need to efficiently produce electric power has gradually increased, and various efforts have been performed in order to reduce generation of pollutants and increase power production since activities for reducing generation of pollutants are increased. One of them is a study on a power generation system using supercritical CO2, which utilizes supercritical carbon dioxide as a working fluid, as disclosed in Korean Patent Laid-open Publication No. 2013-0036180.
The supercritical carbon dioxide simultaneously has a density similar to that of liquid and a viscosity similar to that of gas, thereby enabling the system to be miniaturized and the electric power required for compression and circulation of the fluid to be minimally consumed. In addition, it is easy to handle the supercritical carbon dioxide since the supercritical carbon dioxide has a smaller critical point of 31.4° C. and 72.8 atmospheres, compared to water having a critical point of 373.95° C. and 217.7 atmospheres. When the power generation system using supercritical CO2 is operated at the temperature of 550° C., the system may have about 45% of net power generation efficiency, which is an improved power generation efficiency of 20% or more, compared to existing steam cycles, and the size of a turbo device may be reduced to one several tenth.
Meanwhile, a typical coal-fired thermal power generation system uses an air preheater in order to increase combustion efficiency by preheating air introduced into a boiler from the outside. An example of such an air preheater is disclosed in Korean Patent Laid-open Publication No. 2003-0058645.
The air preheater is typically a rotary air preheater. Outside air is introduced into the air preheater to be heated therein, and the heated air is introduced into the boiler. Combustion gas discharged from the boiler is used to heat outside air through heat exchange between the combustion gas and the outside air in the air preheater, and waste heat in the combustion gas is used in the air preheater.
However, the conventional rotary air preheater has a complicated structure, and a low efficiency since air flows into combustion gas and vice versa. In addition, the air preheater has a problem in that air or gas tends to leak due to gaps occurring therein.